The use of fiber as a nutritional supplement or food additive is widely accepted and used all over the world today. This can be attributed to the general knowledge of the beneficial health effects widely described by various research projects worldwide and the knowledge that most of the population has about the term “fiber”. The following can be mentioned among the beneficial effects:                Improving and/or stabilizing colonic microbiota composition        Improving bowel function (stool consistency, regularity of bowel evacuation, bowel transit regulation, etc.)        Reducing the risk of suffering colon cancer        Reducing the risk of and/or improving the handling of bowel inflammation        Reducing the risk of bowel infection        Modulating the working of the immune system through modifications in colonic microbiota metabolisms        Reducing the risk of obesity, type 2 diabetes, metabolic syndrome, etc., among others.        
Nevertheless, the described physiological effects are mainly determined by the composition and/or type of fiber as well as the compounds associated with it. In this sense, not all types of fibers exert all the described physiological effects, and the degree of the effect observed can also depend to a great extent on their composition and the bioactive compounds associated therewith.
In relation to blood lipid profile modification, fiber, mainly soluble fiber, is considered to exert its effects through its capacity of chelating bile salts produced in the liver through cholesterol. Additionally, it has been described that some of the by-products of colonic fermentation such as short-chain fatty acids (propionic acid, for example) could have a certain effect on the inhibition of HMGCo-A (hydroxymethylglutaryl coenzyme A reductase), a key enzyme in cholesterol synthesis.
In general terms, it can be established that the intake of 2 to 10 g of soluble fiber or viscous fibers a day is associated with a reduction of total cholesterol (−0.045 mmol/L per gram of fiber) and LDL cholesterol (−0.067 mmol/L per gram of fiber), a fact that is proven both in hypercholesterolemic and normocholesterolemic subjects. Nevertheless, HDL cholesterol levels tend to drop (−0.002 mmol/L per gram of fiber) or are not affected after dietary treatments with soluble fiber, which is undesirable according to cardiovascular risk indices. One of the main biochemical cardiovascular risk indicators is the ratio of the serum concentrations of total cholesterol (TC) and HDL, such that the lowest possible values, ideally below 4.5, are desired. The administration of dietary fiber that reduces both total cholesterol and LDL levels and HDL levels does not successfully reduce the TC/HDL ratio, and is therefore not completely effective in reducing cardiovascular risk.
There is certain evidence that some bioactive compounds, for example phytosterols, among others, can affect cholesterol flow through the intestinal epithelium by modifying the expression of the reverse flow (towards the lumen of the intestine) cholesterol transporters ABCG5 and ABCG8, thus reducing the plasma total cholesterol levels, LDL cholesterol levels and possibly increasing HDL cholesterol levels. Nevertheless, no compound that can considerably reduce LDL cholesterol levels while HDL cholesterol levels are increased has been described. For example, a recent meta-analysis describes that consuming 0.6 to 2.5 g of phytosterols a day shows a similar effect in the reduction of both LDL and HDL levels. Even though consuming foods of plant origin, the main source of fiber and bioactive compounds in diet, is known to improve the lipid profile, it is impossible to induce an increase in HDL levels when attempts are made to simulate their consumption through supplementing or other means.
Therefore, there is a need to provide fiber-based preparations capable of reducing total cholesterol and LDL levels while at the same time increasing HDL levels.